The invention relates to union devices for securing flexible tubes, for example in pneumatic logical circuits, where rapid connection and disconnection of tubes is required.
The known union devices can be divided into two categories, those which employ a nozzle inserted in the open end of a tube, and which involve the drawback of considerably restricting the throughflow diameter, and those in which the open end of the tube is inserted in a nozzle or sleeve.
The invention is more particularly concerned with union devices of the latter type for use with flexible but semi-rigid tubes, i.e. which are resistant to radial deformation and hence to constriction of their passageway.
A recent proposal for such a union device has been to provide a split ring of resilient metal with a plurality of flexible tonques each carrying an inwardly directed claw. A toric joint is provided in the split ring which also carries an external sliding sleeve to enable radial deformation of the tonques in the manner of a chuck. These split ring assemblies are fitted onto a union housing by means of a special tool. In use, the end of a tube is pressed into the split ring, and then the sleeve is moved to firmly press the claws into the outer surface of the tube, to prevent unwanted removal. Apart from the complication of this arrangement, the ends of the tubes are liable to be damaged during withdrawal.
Another proposal has been to provide a deformable sleeve into which the end of a tube is freely inserted. An outer ring is then moved axially over the sleeve in order to constrict both the sleeve and the tube to provide a fluid-tight fit. These types suffer the drawback that a localized restriction, albeit a small one, of the inner passageway of the tube is always involed. Also, the smaller the axial extent of this restriction the less reliable is the fluid tightness of the joint, while the provision of a constriction along the whole length of the sleeve involves special tools to axially slide the ring.
An aim of the invention is to provide a union device of simple conception which enables a fluid-tight joint to be obtained rapidly, with practically no restriction of the inner passageway of the tube, and without a risk of damage to the end of the tube.